ES2471147T3 - Hot water installation - Google Patents

Abstract

Hot water installation comprising: a storage container (1) arranged to store hot water; and an external water heating circuit comprising two or more heat sources (9, 8, 4) arranged in series; wherein the storage container has only two connections, a first connection connected as a supply to the external heating circuit and connected as a cold supply (10) to the storage container (1), and a second connection (11) to supply water heat from the external heating circuit to the storage vessel, and to supply hot water from the external heating circuit 10 on demand, so that, during use, the flow through both connections of the storage vessel is reversible , and hot water is supplied either from the storage vessel and / or directly from the external heating circuit.

Description

Hot water facilities

The present invention relates to hot water installations intended for the supply of hot water to bathtubs, showers, toilets and the like, for example for hotels, hospitals, offices, homes and industry. The present facilities have been designed to use low-grade heat that is complemented by higher-grade heat to heat the water to the intended temperature.

Japanese patent document P2000-121157A discloses an installation in which hot water is stored in a storage vessel, and the water is heated in a complex external heating circuit, in which a plurality of heat exchangers is located external arranged in series. Cold water is supplied to the bottom of the container and is drawn from a different outlet near the base of the container, and circulated through the heat exchangers before being returned to the top of the container. Hot water is drawn from the top of the container according to common practice. Similarly, Japanese patent document P2003-74969A discloses a storage container for hot water that is heated in an external heating circuit. Again, the storage container comprises four taps, and in the arrangement shown, the hot water in the storage container does not remain stratified.

Japanese patent document P2004-257590A also discloses a storage vessel that receives a cold water supply, and the hot water outlet leaves said container. As in document P2003-74969A, the water in the container is not stratified. Each of the prior art circuits requires a storage tank with four taps according to common practice. In all cases, cold water is supplied to the container, where it is mixed with the water in said container before being extracted and heated.

An installation according to the present invention is described in the appended claims. An installation according to the present invention is characterized in that the storage container has only two connections, a first connection at the base of the container to supply the external heating circuit connects with the cold water supply to the storage container, and a second connection intended to supply hot water from the external heating circuit to the storage vessel, to fill said container with hot water, or intended to supply hot water from the container to the domestic hot water outlet of the system. The effect of the T-joint is that all water can be supplied from the storage vessel, or from the heating circuit, or from a mixture of both sources. Both individual connections with the container, one at the top and one at the bottom, allow the flow through both connections of the storage container to be reversible, so that hot water can be supplied from the storage container and / or directly from the external heating circuit.

The bi-directional flow allows the variable flow capacity and the variable heat supply capacity of the external heating circuit to be used at full capacity to match the minimum output requirements of the remote heat generator to supply untreated water to the heat exchangers of the system. This is complemented by hot water from the storage tank, so that water is extracted from the storage tank when the demand is too high or too low. The heating circuit replaces the hot water extracted from the tank when the flow is reversed at the outlet. Therefore the stratification of the hot water in the tank is maintained, which enhances the thermal efficiency of the installation and the effective thermal capacity of the container.

Advantageously, a check valve is provided in the external heating circuit to prevent backflow or reverse flow in the circuit. However, the circuit advantageously uses positive displacement pumping to perform this and other functions in the heating circuit.

Among the Japanese patent documents mentioned above, none can provide a complete hot water tank and at the same time heat the incoming cold water, and supply it directly to the taps, or supply hot water directly to the taps when the storage container is filled with cold water, or supply hot water from both the storage vessel and the external heating circuit to meet the maximum demand, or offer the flexibility of such an arrangement of the connections.

The fact of providing an electric heater as (preferably) the last heater before the hot water enters the storage vessel allows less heat to be used to preheat the water in the external circuit. Said heater is a particularly desirable feature of the present invention, since it allows the water in the container to be heated to a temperature suitable for sterilization overnight, with the disinfection interval between 70 ° C and 80 ° C. . If the water is at a temperature of 70-80�C in the storage container, a mixing circuit can allow this water to cool to outlet temperatures suitable for showering and bathing, between 38�C and 46�C (according to the recommendation on water temperature safety).

This feature, which is not described in the prior art, also allows the storage of domestic hot water in the container at lower temperatures suitable for capturing solar thermal energy, which can then be heated.

The present invention has the concrete benefit that the water entering is hard, which causes the deposition of scales in the heat exchangers. Flake deposits are relatively low at temperatures between 40�C and 55�C.

Preferred embodiments of the present invention are especially useful in domestic hot water installations.

Preferred embodiments of the present invention address the problem of how to prevent the development of Legionella bacteria. The present invention relates to a method for heating water and controlling water heating, and the method for controlling circulation within a hot water installation, extraction from the reservoir and recirculation of water that has been extracted and returned to warm up again.

In addition, the present invention addresses the problem of how to control and time the storage of energy in the form of domestic hot water and, using a stratified tank, how to improve the operation of the cogeneration plants. Energy can be provided in the form of heat, for example by solar energy, although any source of energy can be used where the quality or quantity or cost of production changes over time.

A hot water installation according to the present invention comprises a storage container for containing a stored amount of hot water with thermal stratification, an inlet in the lower part of the storage container to receive the water supply, an outlet in the upper part of the container for supplying hot water according to demand, and an external water heating circuit to said storage container, which extends from a first connection in the base and along at least one heat exchanger, to be heated to the temperature final required for hot water, or above it.

In preferred embodiments, the water heating circuit comprises a pump for the circulation of water around a heating circuit from the entrance to the exit of the tank. The circuit further comprises a temperature sensor at the inlet of the tank and a control unit to control the pump so that, when the detected temperature reaches a predetermined value, the pump stops, and when the detected temperature decreases to the temperature of cold water supply, the pump will start. In preferred embodiments, the heating circuit may comprise at least one heat exchanger to provide heat to the water from a heat source, to increase the water temperature to a value between the supply temperature and the value predetermined.

In a preferred embodiment, a shunt is provided around the pump. The function of this bypass is to keep the fixed speed pumps in their curve and provide a minimum flow through the pump when the volume of water pumped by the heat exchanger must be changed. This allows the heat exchanger output to vary.

The bypass may have a sensor or thermostat element so that the liquid whose temperature must be controlled can flow along said thermostat, which improves the response speed of the thermostat.

The thermostat can be arranged in relation to the heat exchanger and the pump so that, even in the event of a pump failure, the thermostat detects the temperature of the water leaving the heat exchanger. This can be achieved by using a plate heat exchanger, with two taps on both sides, and installing it horizontally instead of vertically. By providing a bypass of the upper zone, a convection circuit for the hot fluid can be provided, so that it flows over the sensor with or without pump assistance.

Pipe fittings made of p. ex. Brass and / or copper, attached to the heat exchanger, also allow heat conduction to the sensor.

This arrangement provides functions that plate heat exchangers do not usually present. In the known systems, the sensors are mounted outside the heat exchangers due to the practical problems of introducing temperature sensors into said heat exchangers with only four connections. In a preferred embodiment, the use of a heat exchanger with eight connections allows the easy expulsion of gases from the heat exchanger.

The pump may be of the volumetric type, for example a piston and cylinder pump with a filtration accumulator,

or rotary type.

In the event that the main heat source of a heat exchanger of the heating circuit requires that the main return temperature be lower than a predetermined value (for example, for a condensing boiler of a cogeneration unit), advantageously , the main circuit of the heat exchanger of the present invention may comprise at least one valve, preferably full modulation, to control the main flow and, if necessary, to stop the flow through the main circuit of the heat exchanger. Thus, by controlling the main flow, the main return temperature can vary.

To avoid "dead space" inside the tank, which could accumulate bacteria such as Legionella bacteria, an inlet diffuser can be provided at the bottom of the tank. Said diffuser supplies the cold water entering the tank and disperses it, thus reducing its speed and mixing the contents of the tank, and promoting stratification. If the inlet is a conventional cold water inlet part of an existing hot water cylinder, the diffuser can be made of a flexible material, expandable after insertion through the inlet piece, and with a weight to keep it at the bottom of the cylinder. The tube can be a jacket, which inflates with water pressure as it enters the container.

In addition, to ensure that the tank is filled with hot water, an outlet diffuser is placed to extract the cold water from the bottom of the cylinder through the pump and the external heat exchanger.

If the diffuser does not depend on the pressure of the inlet water to inflate the jacket and allow passage to the water, the inlet and outlet diffuser can be formed as a single unit.

The circuit can operate in various ways to ensure the rapid availability of hot water in a plurality of locations.

In a first mode, the return water of the circuit can be supplied to the suction side of the pump, to be mixed with the secondary heated water. In this mode, the pump performs a double function: it acts to pump water into the tank, and also to recirculate water into the system. The balance of flows around the circuit is achieved by adjusting the regulating valves. Thus, the temperature of the water leaving the heat exchanger increases to heat the return water, so that the mixture of both reaches the required temperature.

In the second mode, the return water of the hot water circuit can be re-supplied to the hottest part of the heating circuit before returning to the tank. If the thermostat is located in the mixed flow from both circuits, that is, the return circulation circuit pumped from the taps and the domestic hot water heating circuit, the water in the heating circuit can be heated to a temperature higher than that required in the sterilization tank.

The present invention, in all its aspects, is defined in the following independent claim, to which reference should be made. The advantageous features are disclosed in the dependent claims.

A preferred embodiment of the present invention is described in more detail below, and takes the form of a hot water installation comprising a storage container for containing a thermally stratified hot water tank; and a water heating circuit external to the storage vessel. Said container comprises, in its lower part, a connection for a cold supply for the water entering the storage container and a supply for the external heating circuit and, in its upper part, a connection for supplying hot water from the external heating circuit to the vessel, and to supply hot water on demand. The hot water installation is especially useful as a domestic hot water installation. Such installation allows existing hot water cylinders to adapt and be suitable for condensing boilers to provide improved conversion of fuel to energy and heating rate for domestic hot water, due to heat exchange to external countercurrent, in comparison With the normal heating coil inside the container.

The embodiments of the present invention will be described in more detail below, by way of examples referring to the drawings in which:

FIGURES 1, 2, 3, 4, 5, 6, 7 and 9 represent seven versions of domestic hot water installations; FIGURES 4A, 4B, 4C and 4D are schematic sections of tanks with convex and concave bases; FIGURE 4E is a schematic section of the upper part of the tank; FIGURE 8 is a vertical schematic section of the intermediate heat exchanger of Fig. 7; FIGURE 10 is a detailed representation of Figure 9; FIGURES 11 and 12 represent alternative arrangements of the embodiment of Figure 1; FIGURE 13 is a detailed representation of the operation of the embodiment of Figure 1; FIGURE 14 represents an alternative arrangement of Figure 3; FIGURE 15 is a detailed representation of Figure 14; Y FIGURES 16 to 18 represent schematic sections of part of a domestic hot water installation.

The systems represented in Figs. 1 to 7 are designed to recover (reheat) a hot water tank using multiple (2 or more) sources of heat. The water to be heated passes through each heat source in series, so it allows you to control the relative amount of energy that is extracted from each heat source.

Although in the figures the exchangers are shown in the vertical plane (which is the plane required for units with four connections to ventilate), the heat exchangers of the present invention can be installed with the surface area of the plate horizontally or in any other plane.

The maximum total efficiency of the system increases by arranging the heat sources so that the heat source with the most efficient operation at low temperatures is used first to heat the cooler water, and the heat source with greater efficiency at elevated temperatures is used the last to heat the water to its final temperature.

Water can be heated by a single heat exchanger, e.g. ex. a solar unit, or a combination of heat exchangers in series.

The system of the present invention uses water stratification when heated to increase heat transfer efficiency, and to minimize and prevent the development of Legionella bacteria, keeping water inside the system at temperatures where it is not Spread Legionella bacteria. The water is heated outside the hot water tank which, due to stratification, contains hot water in its upper part that is at a temperature at which Legionella bacteria is removed over time, and colder water in its lower part at a temperature at which bacteria cannot develop within the period of time required to fill the container with cold water before heating (which would normally be one to two hours). Another way to prevent the spread is to supply water to the bottom of the unit that has already been heated in the external heat exchanger to a temperature (usually higher than 50�C) that eliminates bacteria.

The three sources of heat that are usually taken into account are:

one.

 Main system: normally remote boiler systems, or cogeneration plants that will operate more efficiently with lower main return temperatures, that is, more fuel converted to energy by extracting heat from combustion products.

2.

 Electric heater: used as a source of high temperature, since the efficiency of conversion of electrical energy to heat is not affected by the temperature in the temperature range under consideration.

3.

 Electric heater used as reinforcement and replacement as an alternative heat source.

3rd. Electric heater to offer choices to manage and use the output of a cogeneration plant that produces both electricity and heat, if situations arise in which it is advantageous to provide an electric charge for the cogeneration plant.

The mechanism for this load is the remote control of the time needed to heat the stratified tank, either with heat from the cogeneration plant or from another source of heat or electricity. This is achieved by measuring the available capacity in the tank and the pattern of demands for hot water, by monitoring the tank, either by measuring the level of hot water in the tank or the inlet and outlet flows of the tank and the conditions in which that the tank is full of hot water or cold water. The objective is to offer a way to provide a local thermal energy deposit in buildings, in the form of domestic hot water, as an alternative to known methods in which tanks are used to store the main water for heating in the cogeneration plant� not in the main heat supply system.

Another source of heat can be a solar panel or other renewable energy source that usually provides low temperature heat.

Figure 1 represents a heat source used to heat stored water. The pump 2 circulates cold water, either from the base 7 of the tank inside the storage container 1, or from the lowest point of the tank to the first heat exchanger 5, where it is heated by the heat source 9. The Heat exchanger 5 allows heat to be transferred from the heat source 9 to the water in the tank without mixing the separate circuits. Normally, the heat source 9 is at a relatively low temperature.

After passing through the first heat exchanger 5, the water in the tank passes through another heat exchanger 3 where it is still heated by the main heat source 8.

Finally, the water in the tank passes through an electric heat source 4 and is heated until it reaches the final temperature before returning to the top of the tank 1 through a path 6. If the heat exchangers at an earlier point of the Circuit path are able to increase the water temperature to the desired final temperature, at least the source of electrical heat can be omitted from the circuit.

In the system shown in Figure 2, there are only two sources of heat; the main heat exchanger 3 and the electric heat source 4.

The amount of heat input from the main heat source 8 to the water in the tank can be controlled by altering the flow rate or temperature of the heat source 8 supplied to the main heat exchanger 3.

Similarly, the amount of heat input from the heat source 9 to the water in the tank can be controlled by altering the flow rate or temperature of the heat source 9 supplied to the heat exchanger 5.

The amount of heat input from the electrical source 4 can be set by controlling the power supplied to the electric heating element.

As can be seen in Figure 3, the heating circuit can be connected to a tank 1 by means of a cold supply tap 10 and a heat extraction tap 11. Other taps can also be used such as dedicated taps. In this way, the circuit is adaptable for use in tanks with less efficient methods for heating water, such as those incompatible with the condensation function of boilers or cogeneration facilities, since they cannot provide low water temperatures of main return offered by the embodiments of the present invention.

As can be seen in Figure 4, a diffuser tube 12 or a similar deflector system can be used to combine the cold supply 10 and the supply 7 to the heating circuit in a single tap or pipe within a pipe formation 15 Thus, it is guaranteed that only water is extracted from the lowest point of the tank. Although all the figures show a deposit with a flat bottom, it should be noted that the system of the present invention can be used with deposits having a concave or convex bottom. Diffusers can be introduced for use in diffusers of this type through faucets in existing standard containers. Figures 4A and 4B represent sections of reservoirs with a concave and convex bottom respectively, and also represent how water is injected and extracted from the bottom of the reservoir.

Figures 4C and 4D represent still other alternative sections of the tank 1, with a respectively concave and convex bottom, and pipe formations 15. The pipe formations or connections 15 are for the cold water entering the tank 1 and for supplying said cold water to the external heating circuit. The connections 15 allow the flow of water in two directions within the formation of pipes 15. In Figure 4D a temperature sensor 33 is shown that can detect the temperature of the water at the bottom of the tank 1. Said temperature sensor 33 is � located at the bottom of the tank 1 and projects from the end of the pipe formation 15. A cable 34 with an electrical connection to the sensor 33 extends along the pipe formation 15 and exits from it through a gland in a hole 35 in the wall of the pipe formation 15 outside the reservoir 1. The cable 34 can make an electrical connection with an appropriate device to extract temperature information as required.

A similar pipe formation 15 can be found at the top of the tank 1 as seen in Figure 4E. This formation of pipes 15 serves to supply hot water from the external heating circuit to the container and to supply hot water on demand. It allows hot water to flow in two directions.

A deflector 13 can also be attached to the extraction point at the top of the tank, together with a safety overpressure valve 14. The baffles 12, 13 help prevent turbulence inside the tank 1, and also collaborate in the maintenance of stratification. An alternative arrangement of the baffles would be the placement of a spiral tube, connected by an opening in the upper part of the container, or a disk formed from a material that will take the form of a disk when inserted through said opening, with the presence of distribution holes in said material covering the device, such as PTFE.

The heating speed of the heat sources can be adjusted by altering the water flow rate of the tank 1 through the heat sources 3, 4, 5. The circulation flow rate can be predetermined and set,

or alternatively, it can be varied during operation to achieve different heating and recovery speeds (for example, to ensure that water is available in extraction conditions from the taps, where the heated water is extracted from the tank and also directly from the tank heating circuit). This is especially advantageous since this arrangement allows an improvement in the use of the volume of the tank 1, and complements any extraction with water from the heating circuit. Thus, if for example the temperature of the water drawn from a tap falls below a predetermined level, the supply of the cylinder can be cut off and instead water can be supplied directly from the heating circuit.

The heating input of each heat exchanger is changed or optimized separately and independently, in terms of savings and efficiency of heat exchange against the current, by internal control of the flow in its main circuits, and the temperature of the outlet secondary heat exchanger. The flow rate of circulation can be established by a variable speed pump at a certain speed, controlling the supply of electricity to a fixed speed pump, or using water valves outside the pump (optionally, in conjunction with a branch circuit).

The location of pump 2 within the circuit is not specific. Figure 1 shows how the pump 2 can be placed in the circuit near the base 7 of the tank. Alternatively, Figure 5 shows how the pump 2 can be located adjacent to the electric heat source 4 in conjunction with a return loop 14. Said return loop 14 supplies hot water from the pump 2 back to the output of the main heat exchanger 3. Balancing valves 12 can be used to adjust and set the flow rates around the circuit.

Figure 6 shows how a three-port thermostatic valve can be used to control flow rates through a branch 16 and connection 6. Valve 15 causes water to recirculate through branch 16 until It detects an increase in temperature, and then allows the water to pass to connection 6. Valve 15 works so that the water in the tank reaches a set temperature, which is usually 60-65�C. bypass 16 can inject water into the valve 15 directly from the outlet of the heat exchanger 3, as seen in Figure 7. Thus, the thermostatic valve 15 will detect a main heat input into the heat exchanger 3 without circulation of the deposit flow and return 7, 6.

To obtain a similar effect, the main heat exchanger 3 can be divided into two sections 3 ', 17 as seen in Figure 7. The main heat exchanger / bypass 17 is used to allow the thermostatic valve 15 to detect the Heat input from the main heat source 8, and allow the flow of water from the tank through the main heat exchanger 3 to start.

The use of external electric heating in combination with a heat exchanger and a heat exchanger of a boiler supposes a large part of the energy required to provide domestic hot water produced by heating systems in which the water flow temperature is reduced which is heated when the demand for heating is lower, to control the ambient temperature in buildings. In these circumstances, the water that is heated (for example at 45 ° C) is at an insufficient temperature to provide domestic hot water (which is usually around 60 ° C). The system can also increase the cold water temperature during winter, from approximately 10�C to 20�C to 60�C, or when the temperature is lower than the remaining heating that comes from the electric heater.

By measuring the amount of hot and cold water inside the storage vessel reservoir, either by temperature sensors that detect the stratified interface between hot and cold water, or by measuring the flows of hot and cold water entering and leaving the deposit, information on hot water usage patterns can be obtained to optimize the overall efficiency and cost of heating the water, and that of using a unit comprising a cogeneration plant, to allow choosing the time to The tank is reheated to match the hours at which the operation of the cogeneration plant is optimal to generate electricity and use the heat produced.

The present invention allows existing hot water cylinders to be adapted to be suitable for condensing boilers and, through a selection of appropriate heat exchanger parameters, to provide an improvement in the heating rate for domestic hot water.

In a variation of the system, the arrangement supplies hot water from the heating circuit for the tank directly to the taps, if the temperature of the water coming from the top of the tank decreases, or if said water is mixed with the water in the tank for Reach a set temperature.

Most existing tanks comprise heat exchangers 3, 5 or 4 inside.

Such an arrangement causes a mixture in the tank.

The temperature of the water returning from the heat exchanger must be above the required temperature inside the tank, for example, for a required water temperature of 60�C inside the tank, the main return temperature of the heat exchanger will be� of 65�C.

According to the present invention, the temperature of the main return water from the heat exchanger should only be higher than that of the cold inlet water, for example, 10�C to 25�C. The flow of this main water is controlled by two-way valves that are part of a variable flow main circuit.

The condensation operation requires a return of 50�C or less.

In the installation shown in Figures 9 and 10, the temperature of the water that the thermostat TS1 detects at the inlet 7 is used to control the pump 2. Said pump 2 has a restricted branch 21 controlled by a restriction 22 and operates when required secondary water heating.

Another thermostat TS2 is in the secondary path of the heat exchanger 3 and controls a fully modulable valve 23, which controls the flow of the main heat source 8 until it reaches a sufficiently low value to ensure that the temperature of the main return is below a predetermined value, for example, 30�C. By placing the second thermostat in the secondary path of the heat exchanger 3 and maintaining the flow through it thanks to the pump 2, an immediate response to a change in demand is obtained.

A hot water supply circuit 30 can go from the outlet port 6 to a series of faucets, and comprise a pump 31 that returns the unused hot water at a slightly lower temperature, for example, 50 ° C, to the outlet of the electric heater 4, where it is mixed with the water heated by the heating circuit. To obtain the required tank temperature, for example, 60�C, the heating circuit outlet temperature should be at a temperature higher than that of unused hot water.

Another embodiment of the system is shown in Figures 11 and 12. They are similar to the embodiment of Figure 1, and the same numerical references are used to identify the same characteristics. The external water heating circuit is provided with a non-return valve 100 so that the water flow in said external water heating circuit has a single direction, which coincides with the water flow direction of the pump 2. Water flows in the storage vessel change direction when they absorb

or release heat.

In the embodiment of Figure 11, the connection with the storage container 1 at the bottom of said container is provided with a non-return valve. In the embodiment of Figure 12, the non-return valve is in connection with the storage container 1 at the top of said container. However, the non-return valve 100 can be placed anywhere along the path 6 of the external water heating circuit.

The purpose of the non-return valve 100 is to avoid unusual conditions that may occur when the temperature of the external heat exchanger circuit (although isolated) drops if there has been no circulation and heating of water for a long period. Water cannot circulate for a long period for various reasons. For example, during the night when there is no demand for hot water, when the water in the circuit cools because the main circuits and the heat exchange circuits are closed when the storage container 1 is filled with hot water domestic, or when the heat exchange circuits are not heated because the heating of the tank 1 is timed to be performed at the lowest cost when the cost of heat from a main source is minimized.

When there is a substantial temperature difference between the water in the storage vessel 1 and the water in the external heating circuit, the high density of the cold water in the external heating circuit causes it to descend to the bottom of the tank 1, while hot water with a lower density of the tank that enters the external heating circuit raises its temperature and then cools.

This cooling of the water in the heating circuit can initiate an inverse circulation of the water in the circuit (that is, in the opposite direction to the pump 2 direction).

A benefit of placing a non-return valve 100 in the connection with the storage container 1 at the bottom of said container is that the water that passes through this valve will be mostly fresh or cold water, and therefore the valve 100 It is less likely to develop deposits of solids in the valve produced by lime flakes or other minerals present in the water, which can cause the valve to block and fail.

The non-return valve 100 can be activated to only allow flow in one direction if the temperature of the water circulating in the external heating circuit drops below a specific temperature, if reverse flow is detected, or a combination of the previous. The non-return valve may not be permanently activated. Suitable electronic sensors can be provided in the external heating circuit to turn on and off an electrically activated non-return valve as required, or said valve can act on its own by detecting reverse flow.

This type of non-return valve may also be present in the other embodiments of the system described herein.

Figure 13 represents the flow of water in the external heating circuit of the embodiment of Figure

1. This is the flow of water through the arrangement of heat exchangers 3 and 5 connected in series in the external circuit or secondary circuit that heats the fluid in the tank 1.

The flow in heat exchangers 3 and 5 is a reverse flow. That is, the water flowing in the path of the hot water circuit goes in the opposite direction to the fluid in the separate circuits or main circuits of the heat exchangers 3 and 5, which heats the water in the path of the hot water circuit. .

The temperature of the water in the path of the hot water circuit entering a heat exchanger 3 or 5 is colder than that of the water leaving the heat exchanger. Therefore, the temperature T1 of the secondary water entering the first heat exchanger 5 is lower than the temperature T2 of the water leaving the first heat exchanger 5 and entering the second heat exchanger 3. The temperature T2 is lower than the temperature T3 of the water leaving the second heat exchanger 3 and entering the heat source 4. The temperature T3 is lower than the temperature T4 of the water leaving the heat source 4.

The in the separate circuits or the main circuits of the heat exchangers 3 and 5 has an inlet temperature higher than the outlet. Therefore, the temperature TB of the fluid in the separate circuit or main circuit entering the first heat exchanger 5 is higher than the temperature TA of the fluid exiting said heat exchanger 5. The temperature TD of the fluid in the separate circuit or main circuit entering the second heat exchanger 3 is greater than the temperature TC of the fluid exiting said heat exchanger 3.

By using reverse flow in heat exchangers 3 and 5 the maximum amount of heat can be extracted, beneficially, from any specific main source.

If a main heat source such as solar energy has a variable quality in relation to the heat supply temperature and quantity, the external heat exchanger arrangement with this reverse flow arrangement results in a more effective use of energy. solar. This is whether the solar energy comes directly from a solar panel, or if it comes from a panel attached to a main heating tank associated with the solar panel.

Figures 14 and 15 show a variation of the embodiment of Figure 3.

In this embodiment, a valve 90 is placed between the cold supply 10 and the pipe that passes through the bottom wall of the tank 1.

As mentioned above, said pipe 7 may contain water flowing in two directions. Water can be delivered to reservoir 1 and through said reservoir from the cold supply 10 to the outlet

11. Alternatively, the water can be extracted from the tank 1 by means of the pump 2. The connection 11 at the top of the tank performs a similar bidirectional flow function.

The valve 90 controls the amount of water entering the tank 1 or the amount of water that is removed from said tank under different operating conditions. The valve can be modulated from fully open, through partially open, to fully closed.

When the valve 90 is closed, it prevents the entry into the tank 1 of the water that enters through the cold supply

10. Instead, water passes directly through the external heating circuit.

In addition, when the valve 90 is closed, it prevents reverse circulation in the external heating circuit described above. That is, it acts as a non-return valve.

The conditions to indicate to valve 90 to close and perform this function are that there is no water flow leaving the outlet at the top of the tank 1, and that pump 2 is not pumping (it is off) since tank 1 is full of hot water. The flow of water leaving the outlet of the tank 1 is detected by the temperature sensor TS90, which is located at the outlet of the tank 1. The temperature sensor has an electrical connection with the valve 90 via the control unit 94.

When the tank 1 is filled with cold water, the valve 90 can be closed so that hot water is still supplied to the outlet 11, but only hot water is supplied from the heat exchanger circuit. Alternatively, the valve 90 can modulate the respective flows to provide a mixture of water to the area of the outlet that is supplied with water from the tank 1 and with water from the heating circuit.

Under other conditions, valve 90 is open or partially open.

When the valve 90 is open, the water passes to the tank 1 or is removed from the tank 1 and passes through the external heating circuit to supply hot water as described above.

The effect of the valve 90 when modulating between the open and the closed state is the variation of the relative water flows that are extracted from the external heating circuit and the tank 1.

When water is drawn from the taps 11, two sources of hot water are used, the water in the tank 1 and the water from the external heating circuit. Therefore, the temperature of the water supplied to the taps 11 is affected by the relative amounts of water from the tank 1 and from the heating circuit.

The mixing level of these two sources at the top of the tank 1 at the interface between the water in the tank 1 and the water inlet from the connection 6 to the tank 1 and the outlet of the tank 1 is detected by the sensor TS90 temperature. This detected temperature can be used to modulate the valve 90 and therefore the flow rate through the heat exchanger circuit. Thus, the relative amounts of water and the temperature of the water from the tank 1 and the heating circuit supplied to the taps 11 are controlled.

That is, the temperature sensor TS90 controls the valve 90 at the outlet 11 so that part of the cold water entering through the pipe 10 is passed around the pumped heating circuit, and part is passed through the tank 1 if there is a demand for hot water from exit 11.

An FS90 flow sensor is installed at the outlet 11 to detect a demand for hot water flow from the tank 1. The FS90 flow sensor has an electrical connection to the valve 90 and to the pump 12, via the control unit 92. If the pump 12 is disconnected when the tank 1 is full of hot water, the flow sensor detects where there is a demand for water from the taps 11 and causes the pump to start. It also causes the opening or modulation of the valve 90. The valve 90 and the pump 12 are controlled by the temperature sensor TS90 and the flow sensor FS90.

The TS90 temperature sensor and the FS90 flow sensor are flexible sensors that are located in the tank due to gravity or by means of provisions that cause them to be pushed into position. Alternatively, the sensors may be located within the disk (described in relation to Figure 4) or the bag, which is propelled into position when inserted into the reservoir 1. The disk or bag is used for electrical insulation. The sensors themselves are fixed or woven in the bag or disk.

Alternatively, the sensors are located in the pipe or point of entry to the tank 1.

For all these arrangements, the sensor cables are guided outwardly through glands. The location of the valve 90 in Figures 14 and 15 means that the service life of the valve 90 is longer than the service life of the valve 12 of Figure 3. This is because the valve 90 is fixed in a pipe that It carries mostly cold water for heating, and there is less accumulation of lime and other deposits than in the hot water that passes through the valve 12 of Figure 3. In addition, there is always a means for the expansion of water from the tank 1 and a route for air ventilation from the container.

Figure 16 illustrates in greater detail a preferred arrangement that is similar to the connections in the upper and lower portions of the reservoir 1 illustrated in Figure 3, Figures 4, Figures 4A to 4E and Figure 9. In the connection shown in Figure 16, the liquid flows in different directions in the connection due to different conditions.

Information on this flow is obtained from temperature sensors installed in the pipe or in tank 1 identified as S.

Temperature sensors can be provided in the form of sensors attached to the surface, or sensors in cavities. Preferably, the sensors S are installed in the paths of the water flow, and the signaling cables are carried outside by means of gland arrangements.

S sensors are usually thermal resistances.

Preferably, multiple sensors are installed in each location. Thus, if one sensor fails there is another sensor in the same location to provide the information. Multiple sensors also provide a means of error checking to verify that the signals are valid.

Some typical locations of the S sensors are identified in Figure 16. The S sensors are suspended from the top of the tank 1 and connected to various lengths of electrical cable. The sensors carry a weight so that they are positioned thanks to gravity. The sensors detect the water temperature at different levels of the tank 1.

The sensors can be suspended from the center line of the outlet 11 with the help of a support from the diffuser 12 described above and illustrated in Figure 4.

Figure 16 also shows the usual concave shape of the top of a tank 1, which is a common feature of both horizontal and vertical deposits. Figures 16, 17 and 18 show various pipes for the cold water inlet and outlet of the tank 1, and three types of arrangement of the bottom of the vertical tank 1.

The bottom of the reservoir of Figure 16 is concave. The pipe enters from one side of the tank, towards the bottom. 5 A temperature sensor S is located at the bottom of the pipe and its electrical connection extends along the pipe.

The bottom of the reservoir of Figure 17 is convex. The cold water pipe enters from one side of the tank, towards the bottom. A temperature sensor S is located at the bottom of the pipe and its electrical connection is

10 extends along the pipe.

The bottom of the reservoir of Figure 18 is concave. The cold water pipe enters the base of the tank 1 in the center of the lower part of the tank 1. The electrical connection for a temperature sensor S extends from the top of the tank so that the temperature sensor is located in the opening of the

15 pipe

Such devices for detection and connection allow easy adaptation of existing internal heating vessels to the use of an external heating circuit.

20 This device offers the benefits of water storage with a continuous supply of hot water even when the hot water inside the tank runs out. The volume and flow rate of the water depend on the heat input available from heat sources and heat exchangers, and the respective flow rates through the reservoir and on the heat sources and heat exchangers in series, which can be varied and controlled by pump 2.

Claims (24)

1. Hot water installation comprising: a storage container (1) arranged to store hot water; Y an external water heating circuit comprising two or more heat sources (9, 8, 4) arranged in series; wherein the storage container has only two connections, a first connection connected as a supply to the external heating circuit and connected as a cold supply (10) to the storage container (1), and a second connection (11) to supply water heat from the external heating circuit to the storage vessel, and to supply hot water from the external heating circuit according to demand, so that, during use, the flow through both connections of the storage vessel is reversible, and hot water is supplied either from the storage vessel and / or directly from the external heating circuit.

2.

 Hot water installation according to claim 1, wherein the most effective heat source at low temperatures (9) is first used to heat cold water, and the heat source that works most effectively at high temperatures (8, 4 ) is available to heat the water until it reaches its final temperature.

3.

 Hot water installation according to any one of claims 1 or 2, wherein the heat source used to heat the water to its final temperature (4) is an electric heat source.

Four.

 Hot water installation according to claim 3, wherein the heat source that is used to heat the water initially may be one or more solar panels or a low temperature waste heat.

5.

 Hot water installation according to any of claims 3 or 4, wherein the heat source used to heat the water before reaching the electric heat source may be one or more remote boiler systems, or heat from of a cogeneration plant.

6.

 Hot water installation according to any of the preceding claims, wherein the water heating circuit comprises a pump (2) for the water to circulate around the heating circuit and a unit for controlling the operation of the pump when the temperature detected in the water heating circuit it drops below a predetermined value.

7.

 Hot water installation according to claim 6, wherein the pump is arranged to prioritize the water of the external heating circuit over the water in the storage vessel according to demand.

8.

 Hot water installation according to any of claims 6 or 7, wherein the pump (2) is a positive displacement pump that also acts as a non-return valve in the external heating circuit.

9.

 Hot water installation according to any one of claims 6 to 8, wherein a bypass (16) is provided around the pump to allow a convection flow through the external heating circuit.

10.

 Hot water installation according to claim 9, wherein a sensing element or thermostat (15) is provided in the bypass so that, during operation, the flow of the liquid whose temperature must be controlled along the element is allowed sensor or thermostat (15), and that said thermostat is located in relation to the heat source (s) and the pump so that, even in the event of a pump failure, the detector or thermostat detects the water temperature leaving the external heating circuit.

eleven.

 Hot water installation according to any of the preceding claims, wherein the storage container comprises a cylindrical container arranged for installation with its axis substantially in an upright position.

12.

Installation of hot water according to any of the preceding claims, wherein the water inside the storage container is arranged for vertical stratification, and the hot water occupies the upper part of the container.

13.

 Hot water installation according to claim 12, wherein the cold inlet of the storage vessel is provided with a diffuser (12) to prevent alterations in the stratified level between hot and cold water.

14.

 Hot water installation according to claim 13, wherein the diffuser (12) is made of a flexible material, expandable after insertion through the inlet part of the container.

fifteen.

 Hot water installation according to any of claims 13 or 14, wherein the diffuser (12) is a jacket arranged to swell due to the pressure of the water inlet to the container.

16.

 Installation of hot water according to any one of the preceding claims 13 to 15, wherein the diffuser carries a weight so that it remains at the bottom of the container.

17.

 Installation of hot water according to any of claims 12 to 16, wherein a temperature sensor is arranged to control the pump in the storage container, at a height at which, during operation, the existence of the interface is preferred stratified between the hot and cold layers depending on the level of demand.

18.

 Installation of hot water according to any of claims 12 to 17, wherein two or more temperature sensors (TS1, TS2) are arranged in the storage vessel, at different heights so that the height of the stratified interface between the hot layers and cold can be varied depending on the level of demand.

19.

 Hot water installation according to claim 18, which has means for measuring the flow of hot water leaving the container and / or passing through the cold water supply, to measure the demand for hot water.

twenty.

 Installation of hot water according to any of the preceding claims, comprising a non-return valve (100) in the water heating circuit, arranged to prevent reverse water flow out of the feed vessel and through the water heating circuit .

twenty-one.

 Hot water installation according to claim 19, wherein the non-return valve (100) is located in the connection for the cold supply for the water entering the storage vessel and the water supply to the heating circuit external.

22

 Hot water installation according to any of the preceding claims, wherein the hot water supply circuit is recombined with the external heating circuit before the second, or with the supply connection of the storage container.

2. 3.

 Hot water installation according to any of the preceding claims, wherein the water heating circuit comprises a temperature sensor in one or both connections of the storage vessel for operation of the pump, or a valve for controlling the amount of water heat or stratification in the storage container.

24.

 Hot water installation according to claim 23, which has a modulation valve (90) that attenuates the flow rate in the water heating circuit, and a container for controlling the temperature of the hot water delivered.

 REFERENCES CITED IN THE DESCRIPTION This list of references cited by the applicant is provided solely for the convenience of the reader. It is not part of the European patent document. Although references have been carefully collected, errors or omissions cannot be excluded and the EPO declines all responsibility in this regard.  Patent documents cited in the description � JP P2000121157 A � JP P200425790 A � JP P200374969 A